功能性聚烯烃的开发及应用

功能性聚烯烃在聚烯烃中占有重要地位。本文对最近出现的通过共聚、接枝、有机化学反应、低分子量化、共混复合等方法制得的功能性聚烯烃的开发应用情况进行了论述和评价。     

Toughened polybutyleneterephthalate compounds

The notch sensitivity of polybutyleneterephthalate (PBT) had been improved in a synergistic way, by 30–40 times, by addition of special toughening agents in limited amounts (20–30%). This large toughening effect was studied by high speed photography. Ultimate elongation strain and strain rate at the notch root were measured directly. It was found that the high impact behaviour of toughened PBT is provided by the large amount of plastic strain around the fracture surface. The plastic strain was not observed in the PBT homopolymer during impact fracture, due to its brittle behaviour; on the contrary, it was observed in low speed bending of notched bars. It was concluded that the toughening mechanism of mixed additives is to allow the plastic strain of a PBT matrix at very high strain rates.Now Himont Italia.     

Ductile Phase Toughened Brittle Materials

Toughening of brittle materials by the inclusion of ductile phases is governed by several important factors which include ceramic-ductile phase interfacial bond strength, physical and chemical compatibility between ceramic and ductile phase, geometry and mechanical properties of ductile phase. The present understanding of the effect of these factors on toughening is reviewed and clarified. Continuous ductile phases (network, fibre or plate) are found to be more efficient for the toughening of brittle materials than discrete ductile particles. However, ductile particle toughened brittle materials have the advantages of material homogeneity isotropy and particularly better high temperature properties. It has been demonstrated that the influence of interfacial bond strength is determined by the geometry of the ductile phase in the composites. For the comparatively continuous ductile phase, such as ductile network, fibre or plate, comparatively weak inteffocial bond strength can promote partial debonding of the brittle matrix-ductile phase intedece during crack propagation and is beneficial for toughening. For discrete particulate ductile phase toughened brittle materials, the small gauge length of the ductile phase often results in the ductile phase pull-out during crack propagation which is the main limitation to toughening.Thus strong bond strength is required to ensure the bridging of the crack by the ductile phase.The coefficient of thermal expansion (CTE) mismatch between matrix and ductile phase has also been correlated with the geometry of the ductile phase. In most of the ceramic/metal systems,the CTE of the ductile metal phase is greater than that of the ceramic matrix. In the case of ductile network, fibre or plate, the residual stress created by the CTE mismatch can contribute to toughening through its influence on the initial crack opening stress while the bridging of the crack by the ductile phase is still ensured. However, for discrete ductile particles, the residual stress created by CTE mismatch is liable to cause cracks to by-pass the spherical particles, limiting the efficient use of the inherent toughness of the ductile phase. Low-modulus ductile inclusions are beneficial for the bridging of cracks by the ductile phase. Softer, more ductile inclusions are more effective for the toughening of brittle materials by particulate ductile phase     

树脂增韧及韧性复合材料EI

介绍韧性树脂及其复合材料的发展，树脂及复合材料韧性的表征方法，着重说明层间断裂韧性（Ｇ＿（ＩＣ））和冲击后的压缩强度（ＣＡＩ）作为树脂和复合材料韧性优劣的判据，以此描述树脂和复合材料的发展已被科技界和工业界所接受，还讨论典型韧性树脂基复合材料的性能和韧性树脂基复合材料的应用情况。     

TPU增韧PP共混材料的力学性能

利用双螺杆熔融共混挤出方法制备了TPU(热塑性聚氨酯弹性体)增韧PP(聚丙烯)新材料。考察了两种聚酯型TPU(TPU1和TPU2)和两种增容剂[三元乙丙橡胶接枝马来酸酐(EPDM-g- MAH)和乙烯-辛烯共聚物接枝马来酸酐(POE-g-MAH)]对PP/TPU的力学行为的影响。结果表明,TPU2较TPU1能更有效的改善PP的缺口冲击强度,TPU1则使PP/TPU保持较高的强度和刚性保留率,且加入5质量份的TPU较为适宜;加入适量的EPDM-g-MAH较POE-g-MAH可以更有效地改善PP/TPU的韧性、强度和刚度。     

SBS离聚体研究

本文初步探索了SBS离聚体的制备方法，证明了这种离聚体的存在，并对其性能进行了一些试验。实验发现SBS离聚体对金属及玻璃有良好的粘合力，有一定开发价值。     

离聚体及其高分子共混体系 (Ⅰ)

扼要介绍了离聚体的种类、结构、性能和应用。离聚体可按连接基团的电性、离子基团在主链上的分布、基体的性质而分成各种不同类型。离聚体中的离子基团发生聚集,受基团种类、分子链、基团含量等因素影响,形成如多重离子对、离子簇、桥键、络合体等聚集结构.离聚体被广泛用作包装材料、泡沫材料、高尔夫球及保龄球材料等。     

原位增韧SiC-YAG复相陶瓷的致密化

以β－ＳｉＣ粉加入少量作为晶种的α－ＳｉＣ为起始原料,通过高温热处理过程中的相变和长柱状晶粒生长来制备原位增韧ＳｉＣ基复相陶瓷;调整埋烧工艺控制高温热处理过程中液相挥发和保持稳定的化学计量比,以保证上全部晶化为ＹＡＧ相,着重解决了长柱状晶粒生长过程中的致密化。发现在完全形成紧密的网络状结构之前,长柱状晶粒的形成可能延缓致密化速率,但不会由此中止致密化过程。通过调整热处理条件,制备得到了完全致密化（     

Strain-Recovery Kinetics in Rubber Toughened Polymethylmethacrylate

The viscoelastic nature of polymers influences the material’s behaviour not only during its deformation up to strains beyond yielding, but also during and after its unloading. In the present work the recovery of the strain after the removal of the applied stress was studied as a function of time and temperature on rubber toughened polymethylmethacrylates (RTPMMAs). Constant strain rate tests under uniaxial tensile loading were performed at room temperature on three RTPMMAs, differing in dispersed phase content. Identical samples were deformed up to the same strain level and then unloaded. The residual strain was measured as a function of time at different constant temperatures. By applying a time–temperature equivalence, a residual strain versus time master curve was obtained and the relevant shift factors were determined. Isothermal strain recovery on samples deformed up to the same strain was also measured at different temperatures, in the range between room temperature and the material’s glass transition temperature. The residual strain after a given time was plotted as a function of temperature, obtaining an isochronous strain-recovery curve. Using the appropriate shift factors, an isothermal strain-recovery curve was then determined. The latter and the strain-recovery master curve are similar in the range of time over which recovery takes place, although an effect of the applied strain level on the curves’ shape was observed. The effects of the applied strain level and of the rubber particles content on the strain-recovery kinetics were evaluated.     

杜仲胶对聚乳酸的增韧改性

通过熔融共混的方法,采用生物基高分子材料杜仲胶(EUG)对聚乳酸(PLA)进行增韧改性,并制备了PLA/EUG共混物。采用扫描电子显微镜、广角X射线衍射、差示扫描量热分析、动态力学性能测试和旋转流变仪表征了PLA/EUG共混物的相结构、结晶性能、热性能、动态力学性能和流变性能。实验结果表明,聚乳酸与杜仲胶为典型的热力学不相容体系;EUG以微米及亚微米的尺寸分散在聚乳酸中。通过对PLA/EUG共混物的拉伸性能和力学性能研究,发现EUG的加入明显地改变了共混物的拉伸行为,由纯PLA的脆性断裂向韧性断裂转变。当PLA/EUG共混物中PLA/EUG的质量比为90/10时,共混物的断裂伸长率较纯PLA提高了14倍,缺口冲击强度提高了5.8倍。共混物拉伸断面照片表明基体在断裂前发生了明显的塑性变形,在断裂过程中吸收了相当大的能量,从而使得共混物的韧性得以提高。EUG能有效地改善PLA的韧性,可以作为新型的聚乳酸增韧改性剂。     

氧化锆增韧陶瓷的相变及相变增韧

本文阐述了氧化锆增韧陶瓷（ＺＴＣ）的相变增韧机理，并探讨了热处理工艺对ＺＴＣ的相变及显微组织的影响规律。     

羧基遥爪热致性主链液晶离聚物的合成与表征

以对羟基苯甲酸甲酯和1,4-丁二醇为主要原料,经熔融酯交换合成介晶基元双(对羟基苯甲酸)丁二醇酯(BBHB);以四氯乙烷为溶剂,采用溶液缩聚法将BBHB与适量的对苯二甲酰氯(TPC)反应,经Na2CO3溶液处理,合成端基为羧基的液晶离聚物。通过红外光谱等分析对它们的化学结构进行了表征。表明:所合成的液晶离聚物P1~P3为纹影织构,属于典型的向列型液晶,液晶相区间为100℃左右,羧基对液晶区间和玻璃化转变温度(Tg)、熔融温度(Tm)、相转变温度(Tc)影响不大。     

液体端羧基丁腈（CTBN）增韧环氧树脂的研究EI

本文主要是综述ＣＴＢＮ对环氧树脂进行增韧改性，重点讨论了影响增韧效果的多方面因素，并对其机理作了介绍。     

Wear Characteristics of Zirconia Toughened Ceramic Drawing Dies

Wear resistance of several zirconia toughened ceramics in comparison with a metal-ceramic CoWC has been studied in drawing wire field test. Result indicates that the harder the ceramic die, the longer the service life. Excellent wear resistance of ceramic die is obtained with a very high hardness (19 GPa). The service life is nearly three times that of Co-WC die. SEM observation on wear surfaces showed that material removal is mainly caused by plastic flow and ploughing process. But when the ceramic is composed of zirconia, alumina and some titanium carbide, micro-chipping and tribochemical reaction take place, and wear rate increases. Wear and friction induced martensite was detected by XRD. The T-M (tetragonal to monoclinic) phase transformation has a contribution to inhibiting microfracture.     

无黏结剂层状BN增韧cBN刀具材料的研究

无粘结剂cBN材料制作的切削刀具韧性较差, 并且这种材料的合成压力高。为此, 本研究在工业压力下制备了超硬、高韧的新型无粘结剂层状BN增韧cBN (Lt-cBN)块材, 通过切削硬质合金实验, 分析了Lt-cBN材料内部微观结构对其切削性能和耐磨性的影响。研究结果表明: Lt-cBN材料的韧性高达8.5 MPa·m^1/2, 可超精密切削硬质合金, 获得了粗糙度R_a低于10 nm的超光滑表面; Lt-cBN材料内部存在少量层状BN, 不仅提高了韧性, 还降低了表层材料的非晶化程度及磨损速率; 相对于商品化的纯相cBN材料, Lt-cBN材料展现出更好的切削性能和耐磨性; Lt-cBN材料的主要磨损形式为后刀面的部分非晶化, 并在摩擦作用下逐渐被去除而导致的磨料磨损。     

纳米有机黏土/聚醚砜增韧环氧树脂复合材料研究

制备了新型的有机黏土/聚醚砜/环氧树脂纳米复合材料并对其微结构和增韧机理进行了研究.此纳米材料由半互穿网络结构的聚醚砜/环氧树脂基体和有序剥离形态的有机黏土组成.由于有机黏土和聚醚砜的加入大幅增加了环氧树脂的断裂韧性,并且出现了双增韧剂的协同增韧效应.增韧机理包括两个部分:一方面聚醚砜的加入形成了半互穿网络结构增加了基...     

“离位”增韧复合材料准静态压入损伤特性研究

采用“离位”增韧技术对双马来酰亚胺复合材料层压板进行了层间增韧,然后对增韧和未增韧的两种双马复合材料层压板进行准静态压入及冲击后压缩剩余强度试验研究,并用超声C扫描和热揭层对层压板的损伤进行测量.结果表明:经过“离位”增韧的双马复合材料层压板层间形成了热塑性树脂/热固性树脂双连续的结构,该结构不仅能抑制增韧层压板的内部损伤面积,改善损伤阻抗,使其表面凹坑深度更明显,而且还大幅提高了其损伤容限.     

PET/苯乙烯-丙烯酸钠离聚物的结晶及熔融行为

采用差示扫描量热仪(DSC)研究了离聚物苯乙烯-丙烯酸钠对聚对苯二甲酸乙二酯(PET)的结晶行为及熔融行为的影响。结果表明,苯乙烯-丙烯酸钠离聚物能够诱导PET异相成核,从而大幅度提高PET的熔融结晶温度和降低冷结晶温度,实现PET在高温区和低温区结晶速率的同时提高,并使PET在等温熔融结晶过程的Avrami指数n增加。同时,苯乙烯-丙烯酸钠的加入改变了PET的熔融行为,同等结晶温度下PET/苯乙烯-丙烯酸钠离聚物的多重熔融峰中的峰II温度值大于纯PET。     

刚性填料粒子增韧HDPE及其增韧机理

在总结以往研究工作的基础上，侧重研究了HDPE基复合材料界面应力的诱导结晶效应及其与材料性能间关系，重点讨论了CaCO3／HDPE填充体系的界面粘合性，以及CaCO3粒径、粒径分布、含量及其试样熔体冷却速率等与其基体的诱导结晶效应及材料韧性间关系，并由此结合介绍了相应的韧性机理、增韧模型及其相关的基体结晶动力学验证结果。